fix(filter): preserve inline comment markers in code

[andiahmads]

Summary

rtk read --level minimal no longer drops valid source lines just because they contain comment-looking markers inside strings or inline expressions. Before this fix, a Rust line like let glob = "packages/*"; could enter block-comment mode and hide that line plus following code until a later */ appeared.

The filter now treats block comments as removable only when the trimmed line starts with the block-comment opener, preserving inline markers while still removing full-line single-line and multi-line block comments.

Closes #2385.

Testing

• rtk cargo test core::filter
• rtk cargo fmt --all --check
• rtk cargo test
• rtk cargo clippy --all-targets

Post-Deploy Monitoring & Validation

No additional operational monitoring required. This is a local CLI filtering fix with regression coverage and no service, deployment, or runtime infrastructure surface.

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[CLAassistant]

All committers have signed the CLA.

[KuSh]

Closing in favour of #2397, which makes the identical one line change for issue #2385, from contains to starts_with in the block comment opener, and carries wider regression coverage and a green CI run. Merging it makes this change redundant. Review and comments are very welcome on #2397, or reply here if your version covers a case it misses.